Internal combustion engine fuel



United States Patent Ofilice 3,035,905 Patented May 22, 1962 3,035,905 INTERNAL COMBUSTION ENGINE FUEL James L. Keller, Brea, Calif., assignor to Union Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing. Filed Feb. 4, 1958, Ser. No. 713,090

1 Claims. (Cl. 4458) This invention relates to multi-purpose gasoline additives and particularly to fuels containing these additives. It relates more particularly to the spark ignition internal combustion engine fuel containing an additive material which imparts detergency, improves color and gum stability, and reduces pre-ignition induced by deposits in the combustion chambers of internal combustion engines.

The addition of various surface-active agents to gasoline to impart detergency is well known. Generally these materials contain polar groups that are acidic or at least have an acid reaction, thus sulfonic acids, naphthenic acids, or various metal or non-metal salts of these acids have been used for this purpose. Such materials sometimes impart anti-corrosion or anti-rusting characteristics as well as detergency.

The term detergency as used herein, refers to the ability of the gasoline to prevent or reduce deposits in carburetors. Without detergent additives there is generally a tendency for deposits to be produced at critical points in the carburetor, such as the body wall of the carburetor opposite and possibly slightly below the closed or idle position of the throttle plate. As deposits build up at this point, the clearance between the throttle plate and the body wall becomes less and less for a given setting, and as the clearance is reduced the amount of air passing the throttle plate for a given amount of fuel is reduced, the air-fuel mixture reaching the combustion chamber becomes richer'than it should be for satisfactory engine operation. Carburetors in which such deposits have formed must be cleaned before they can satisfactorily perform their intended function. Moreover, gasolines tend to cause deposits in other areas of the carburetor such as jets and the like, resulting in ineilicient and uncontrollable operation of the carburetor.

The deposits above referred to may be due in part to gums present in the gasoline, but it is believed that they are due, to a great extent at least, to crank case vapors vented from the crank case, exhaust vapors, dust, smoke, etc. The air cleaners employed on automotive engines do not appear to efiectively remove these contaminants. Regardless of the theory as to the source of these deposits, it is found that the described deposits occur to the greatest extent in stop-and-go city traffic driving, where the chances of obtaining air contaminated with these vapors getting into the carburetor are greatest.

In addition to the problem of preventing carburetor deposits, other problems arise in connection with the operation of spark ignition internal combustion engines. One having extreme importance is that of pre-ignition in the combustion chamber. By pre-ignition is meant ignition of the fuel charge in the combustion chamber prior to the ignition caused by the spark. Thus, under certain conditions, ignition of the fuel which is partially compressed in the combustion chamber, takes place probably because of glowing combustion chamber deposits, the temperature of such deposits being high enough to actually ignite the gasoline-air mixture. Ignition of the mixture thus occurs sooner than desired on the compression stroke, rather than at the optimum time just immediately prior to the power stroke. This causes loss in power and knocking of the engine. In a clean engine where deposits have not formed, pre-ignition does not occur.

Various compounds have been added to gasoline to reduce the tendency of deposits to cause pre-ignition. Various volatile phosphorus compounds have been employed for this purpose and are found to have at least some eifect in reducing pre-ignition.

It is an object of the present invention to provide a single additive which will reduce or prevent the formation of objectionable deposits in carburetors and which will reduce or prevent pre-ignition.

Another object of this invention is to provide an automotive fuel which reduces or prevents carburetor deposits and also prevents pre-ignition in the combustion chamber of internal combustion engines.

Another object of this invention is to provide a gasoline suitable for use in modern high-compression automotive engines, which is stable in storage, which pre vents or reduces carburetor deposits, and which does not contribute to the formation of objectionable deposits in intake ports and on intake valves.

A still further object of this invention is to provide a stable gasoline which does not cause corrosion or rusting of ferrous metal storage containers, fuel tanks and the like, which reduces or prevents the build-up of deposits in carburetors, which reduces or prevents preignition in internal combustion engines and which does not permit the undue formation of deposits at any point in the induction system of such engine s.

These and other objects of this invention, which will be apparent as the description thereof proceeds, are attained by adding to gasolines which are deficient in the ability to prevent objectionable carburetor deposits and to operate in automotive or other internal combustion engines without pre-ignition occurring, a compound prepared by reacting an aliphatic amine with a diester of phosphoric acid and having the general structural formula:

R'o R" I in which R and R are the same or different alkyl, cycloalkyl, alkylene or alkaryl radicals, having 6 to 22 carbon atoms, R" and R represent hydrogen or the same or diiferent alkyl, alkylene or cycloalkyl radicals having 6 to 18 carbon atoms, x is an integer of 1 to 5, and R is a hydrogen atom or an alkyl radical of 1 to 4 carbon atoms, the total carbon atoms in the group being 2 to 10. These compounds are prepared by reacting 1 mol of a diester of phosphoric acid with 1 mol of an aliphatic diamine, the reaction being one of salt formation. Using the indicated reacting ratio one free primary or secondary amino group, depending upon the diamine employed, is present in the final compound.

The final product, which will be referred to herein as a salt, is readily formed by reacting the diester with the diamine, preferably in solution in a solvent, e.g., naphtha. The reaction takes place at room temperature. With an impure diester, such as one containing some monoester of phosphoric acid, the salt formed from the monoester is insoluble in the solvent and may readily be separated from the salt of the diester, which is soluble, by decantation, filtration or the like.

The phosphate diesters used in preparing the salts are well known in the art and need not be further described. They are obtained, among other ways, by reacting a hydroxy organic compound, such as an alcohol, with P 0 using a reacting ratio of 4 mols of the alcohol to 1 mol of phosphorus pentoxide. Single alcohols or mixtures of alcohols may be employed.

The diamines useful in preparing the salts of this invention are also well known chemical compounds many of which are available commercially.

Besides many others, the compounds used in preparing the salts of this invention, which when added to gasoline impart detergency, storage stability, and the like, and reduce preignition tendency of the fuel, include the following. Each of these diesters may be reacted with each of the diamines listed to produce the salts which are effective for the purposes described. It will be noted that each of the diamines disclosed herein is an aliphatic hydrocarbon diamine containing no substituents other than hydrocarbon substituents. Moreover, these compounds have not more than one N-hydrocarbon substituent.

Diesters of Phosphoric Acid Diamines Dioctyl phosphate. Dideeyl phosphate. Didodecyl phosphate. Ditetradecyl phosphate. Dioleyl phosphate. Dihexadecyl phosphate. Dioctadecyl phosphate. Mixtures of hexadeoyl and octadecyl phosphates. Dicyclohexyl phosphate. Di(methyl cyclohexyl) phos- Ditolyl phosphate.

Phosphoric acid diesters pre pared from mixtures of tallow fatty alcohols.

Phosphoric acid diesters prepared from mixtures of coconut fatty alcohols.

phate. Di (butylcyclohexyl) phosphate.

Ethylene diarnine. 1,2-propylene diamine. 1,3-propylene diamine. 1,2-butylene diamine. 1,4-butylene diarnme. 1,5-amylene diamine. 1,6hexylene diamine. 1,2-hexylene dlamine. 1,10-decylene diamine.

N-hesyl ethylene diamine.

N -dodecyl ethylene diamine. N hexadecyl ethylene diamine. Noctadeeyl ethylene diamine. N-cyclohexyl propylene diamine.

N-methylcyolohexyl ethylene diamine.

N-oleyl propylene diamine.

Duomeen T.

Duomeen S.

Phosphoric acid diesters pre- Duomeen 0.

prepared from mixtures of soya fatty alcohols.

The Duomeens listed above are substituted diamines of the formula XNH(CH -NH where X is an alkyl radical or a mixture of alkyl radicals obtained from fatty alcohols. Duomeen T is the product obtained using the fatty alcohols obtained from the fatty acids of tallow, Duomeen S from soya fatty acids and Duomeen C from coconut fatty acids.

The salts suitable for use in gasoline and having the characteristics described herein, may be prepared from single diesters and diamines as well as from various mixtures of either one or both of the above reactants.

Amounts of amine salt to be added to gasoline to make the stable, detergent gasoline having reduced preignition characteristics will be between 0.00005% and about 0.5% by weight of the fuel. When detergency is the main requirement between about 0.00005 and about 0.005% is suflflcient in most cases. To obtain the maximum pro-ignition effect as much as 0.05% or more, such as 0.5%, may be employed depending upon the amount of T.E.L. in the fuel. Generally between about 0.0004% and about 0.05% of the amine salt will impart the desired detergency and pre-ignition control.

Although addition of the described amine salts in the proportions indicated will produce the effects described it is found that with the use of a gasoline containing these salts there is an increase in the induction system deposits particularly at intake ports and on the intake valves. This increase in induction system deposits can be greatly reduced or entirely eliminated by incorporating in the gasoline along with the amine salt a small percentage of a medium viscosity paraflinc mineral lubricating oil. Although it may be an untreated paraffinic distillate oil providing it is of low wax content it is preferably a solvent treated and dewaxed paraffinic distillate. It will have a viscosity at 100 F. of 200 to 700 SSU, a viscosity at 210 F. of between about 42 and 78 SSU, a viscosity index above 70, an A.P.I. gravity of 32 to 26.5, and a flash point of at least about 400 F. An ideal hydrocarbon oil to be used will have a viscosity of about 320 SSU at 100 F. and at 210 F. of about 52.2, a V.I. of about 85, a flash point of 445 F. and an A.P.I. gravity of about 28.6. A mineral lubricating oil having these characteristics is referred to herein as 300 neutral oil and is a solvent treated and dewaxed Western paraflinic mineral oil distillate.

It is essential that the hydrocarbon oil employed as the second additive of our additive combination have a viscosity in the range indicated and a flash point above 400 F. since lighter oils do not appear to be effective in reducing or preventing induction system deposits, e.g., intake valve deposits and heavier oils tend to increase combustion chamber and exhaust valve deposits.

The amount of hydrocarbon oil to be used will be between about 0.006% and about 0.6% by weight of the finished composition. Preferably between about 0.02 and 0.2% by weight of hydrocarbon oil will be employed. An ideal amount is about 0.06% by weight.

lthough the function of the hydrocarbon oil is to reduce deposits in the induction system, particularly in the intake ports and on intake valves and the like, the manner in which this is accomplished is not known. Possibly a part of the function of the oil is that it acts as a carrier for the principal additive of this invention, i.e., the diamine salt, and prevents its deposition in the induction system particularly at a point Where the fuel is vaporized.

Gasolines or automotive fuels to which the substituted diamine salt, With or without hydrocarbon oil, is to be added and in which these additives perform the functions described include substantially all grades of gasoline presently being employed in automotive and internal combustion aircraft engines. Such gasolines may be prepared from saturated hydrocarbons, e.g., straight-run stocks, alkylation products, and the like, with or without gum inhibitors, and with or Without soluble lead compounds as for example tetraethyl lead, T.E.L., or ethyl fluid. Suitable gasolines may contain as much as about 5 ml. of T.E.L. per gallon, such amounts being used commercially in aviation gasolines. The gasolines may be made wholly or partially from cracked stocks, which stocks may be obtained by thermal and/or catalytic cracking methods. In such case, the gasolines will contain gum inhibitors and may or may not contain T.E.L. Generally automotive and aircraft gasolines contain both straight-run and cracked stocks with or without alkylated hydrocarbons, reformed hydrocarbons and the like. The methods of preparation of straight-run, alkylated, reformed and cracked stocks for blending in the preparation of automotive gasolines, aircraft gasolines, and the like, are well known and need not be further described. Gasolines suitable for use in present day antomotive engines with which this invention is primarily concerned will generally have the characteristics shown in Table I and it is primarily to gasolines of the character indicated to which the additives of this invention are added and found to be effective.

TABLE I Properties 0 Typical Automotive Gasolines Determined by ASTM Method D-381. b ASTM Method D-Sfi.

The above data were obtained on two commercial gasolines of the grades indicated and are believed to be typical of commercial gasolines marketed at the present time. These gasolines contain 2-3 ml. of ethyl fluid per gallon and 5 to 15 pounds of a phenolic type gum inhibitor per 1000 barrels. It is to be pointed out that the usefulness of the additives of this invention is not limited to gasolines of the types indicated as would be understood in the art. The same additives are etfective in gasolines of lower or higher volatility as well as gasolines having lower or higher knock rating, many of which gasolines are presently commercially available. Gasolines which contain gum inhibitors may contain single materials or combinations of inhibitors. The use of gum inhibitors is well known in the art and need not be further described. It might be pointed out however that the inhibitors are generally aromatic compounds containing amino and/or hydroxyl groups and it should be mentioned further that the particular gum inhibitor or inhibitors employed does not appear to have any appreciable effect on the ability of the described additives to perform the functions described herein. When gum inhibitors are present they are employed in amounts ranging from about 2 to about 40 pounds per 1000 barrels.

The substituted diarnine salts and hydrocarbon oil are soluble in gasoline, and preparation of gasolines containing small amounts of these materials presents no unusual blending problems. If desired the salt or the salt and oil may be dissolved in small amounts of the gasoline and the concentrate thus obtained added and mixed with the gasoline.

Various tests have been used to determine the eliect of the additives of this invention in improving the characteristics of gasoline in respect to their ability to reduce or prevent carburetor deposits and deposits in other portions of the induction systems of spark ignition internal combustion engines. Also a test has been developed to determine pre-ignition when used in an engine. These tests and the results obtained with these tests are described below.

DETERGENCY TEST A test designed to show the ability of a fuel to prevent the formation of deposits in throat or throttle section of a carburetor has been developed and used in order to determine the effectiveness of various detergent additives in preventing such deposits. In this test conditions present in the throat of a carburetor have been simulated in that gasoline, air and exhaust from an engine are pulled into a glass chamber by means of suction, entry to the chamber being through a slot 1 inch long and 0.012 inch wide located in such a position that the gasoline, air and exhaust gases impinge on and pass downward over the surface of a l by 2.5 inch strip of bright aluminum foil. Because of partial vacuum in the chamber partial vaporization of the liquid fuel occurs in the same manner as it does in a carburetor. In this test deposits form on the aluminum strip just as they do on the walls of a carburetor throat.

In the test the gasoline is fed by gravity at the rate of 40 ml. per minute to the slot above referred to. Vacuum is applied to the chamber to pull air and fuel downward over the test strip. Air entering the chamber is contaminated with the exhaust gases produced by a one cylinder, one horsepower gasoline engine operated with a rich fuel mixture. The exhaust from this engine is passed through three knock-out chambers so as to separate and remove materials present in the exhaust which are liquid at ordinary temperatures.

In carrying out this test in the simulated carburetor throat, after the test strip is wet with gasoline, air contaminated with exhaust is pulled into the chamber and passed in contact with the aluminum strip. Gasoline, at the rate indicated above is permitted to flow down the aluminum strip for a period of two minutes then the supply is shut ofi for two minutes. This cycle is repeated 4 times, the total time of test being 16 minutes.

At the end of the test the amount of deposit on the aluminum test strip is evaluated visually. The proportion of the area of the strip stained with deposits is determined and the relative thickness of the deposit is estimated by observing blackness of the deposit. The detergency is rated visually as being poor, indicating a dark deposit over much of the surface area of the test strip, to very good, indicating a substantially clean test strip. So that variations in conditions of operation are not refiected in test results, blank runs are made at close intervals. Thus the base gasoline to which additives being tested are added will be run at the start of a period of tests and run again at intervals to be sure that conditions of operation are maintained such that comparable results are obtained in a series of tests.

In the following table as well as in Tables III, IV and V, all percentages art given in percent by Weight. Moreover, due to the fact that the additives are diificult to name they are referred to as salts of a specific phosphoric acid diester with a specific diamine. In all cases 1 mol of the phosphoric acid diester is reacted with 1 mol of the diainine to obtain the salt. Thus the salt will in all cases contain 1 free or unneutralized amino group. As an example, the compound referred -to as the salt of dioleyl phosphate and ethylene diamine w1ll have the formula:

C13H35O O H It I /P-ONHCH2CH2-NH2 C18H35 O H TABLE 11 Detergency Test Fuel Detergency No. Composition 1 Base fuel 5 Poor. 2 Fuel N o. 1 plus 0.005% of the salt of dioleyl Good.

phosphate and ethylene diamine. 3 Fuel No. 2 plus 0.06% 300 neutral oil Do. 4 Fuel N o. 1 plus 0.005% of the salt of di(methyl- Do.

cyclohcs'yl) phosphate and 1,2-propylene diamine. 5 Fuel N o. 4 plus 0.06% 300 neutral oil Do. 6..-"--- Fuel N o. 1 plus 0.0005% of the salt of diisooctyl Fair-good.

phosphate and Duomeen T. 7 Fuel No. 6 plus 0.006% 300 neutral oil Do. 8 Fuel N o. 1 plus 0.05% of the salt of ditolyl phos- Very good.

phate and Duomeen S. 9 Fuel No. 8 plus 0.6% 300 neutral oil Do. 10 Fuel N o. 1 plus 0.005% of the salt of dioctadecyl Good.

phosphate and 1,4butylene diamine. 1L Fuel No. 1 plus 0.005% of the salt of didodecyl Do.

phosphate and Duomecn O. 12 Fuel N o. 1 plus 0.005% of the salt of phosphoric Very good. acid diesters of coconut fatty alcohols and N -hexyl ethylene diamine. Fuel N o. 1 plus 0.05% of the salt of dioleyl phos- Do.

phate and 1,2-propylene diamine. Base iuel b Poor. Fuel No. 14 plus 0.005% of the salt of dioleyl Good.

phosphate and ethylene diamine. Fuel No. 15 plus 0.06% 300 neutral oil Do. Fuel N o. 14 plus 0.005% of the salt of diisooctyl D0.

phosphate and 1,3-propylene diamine. Fuel No. 14 plus 0.06% 300 neutral oil Poor. Fuel No. 14 plus 0.30% 300 neutral oil- Do. Fuel N o. 1 plus 300 neutral oil D0.

This base fuel is a premium grade gasoline as described in Table I, containing 3.0 ml. '1.E.L. gal.

This base fuel corresponds to the regular grade gasoline described in Table I, containing 2 ml. T.E.L./ gal.

The above data show that whereas the detergency of the base fuel is poor, fuels to which the amine salts of this invention have been added, give good to very good detergency. Since much work which has been carried out indicates that the detergency shown in this test corresponds to the detergency in automotive carburetors operating in connection with automotive engines, it is apparent that gasolines containing these amine salts do have the ability to prevent the build-up of deposits in automotive carburetors. The presence of oil such as 300 neutral oil does not appreciably aiiect the detergency. It does serve other purposes as will be shown hereinbelow.

PRE-IGNITION TEST In order to determine the ability of the additives of this invention to prevent or at least reduce the tendency of a gasoline to ignite in an engine prior to a spark induced ignition, an engine and pre-i nition counter system has been used on fuels with and without the amine salts of this invention. The engine employed is a Labeco D-Sl single cylinder integral barrel engine using 1951 Oldsmobile type head, the engine having a 12/1 compression ratio. This engine is connected to a dynamometer so that it can be operated under load. A pre-ignition measuring device comprising an auxiliary electrode gap located in the combustion chamber and an electronic counting circuit which counts only the ignitions occurring prior to the spark induced ignition. Such counting devices are well known in the art and need not be further described.

In carrying out the test the engine is operated on base fuel using the following 12 minute cycle which is repeated until equilibrium conditions are attained. This requires between about 60 and 100 hours of operation. The 12 minute cycle involves operating:

Step 135 seconds at idle Step 245 seconds at part throttle Step 345 seconds at idle Steps 2 and 3 are repeated alternately 8 and 7 times respectively, and the cycle is finished with step 4l0 seconds at full throttle. This cycle is used since it approaches normal driving conditions.

After equilibrium has been established with the base fuel and the number of pre-ignitions per full throttle cycle or hour has been determined, the fuel containing additive is used and operation of the engine continued. The operation is continued until equilibrium is again established. This requires between 8 and 24 hours. The efiect of the additive is then expresed as Pro-ignition Index, P; which is calculated as follows:

where P is the equilibrium pre-ignition rate of the base fuel and P is the equilibrium pre-ignition' rate of the additive fuel. In starting a new test the engine is disassembled and cleaned and then restarted on base fuel.

In this test the pre-ignition index of fuels containing amine salts of this invention are shown below. The fuels are listed by number and are described in Table II.

TABLE III Preignition Index T est Fuel No. P 2 92 'It will be observed that in every case the preignition rate of the fuel containing additive is less than the rate of the base fuel without additive as indicated by the preignition index values shown in the above table. P is less than 100 in every instance.

COLOR STABILITY TEST Samples of base fuel and fuelcontaining the additives of this invention have been aged at 110 F. for periods of two weeks and the color change observed after this period. The base fuels yellowed appreciably during this period of exposure, whereas those samplesof fuels containing the amine salt additives of this invention showed little or no change. -It was found that the gum content vof the gasolines increased on exposure in the case of base fuels 1 and 14 but there was substantially less change on samples of these fuels containing amine salts.

ROAD LOAD DETERGENCY TEST This test is run in a standard six cylinder 1952 Chevrolet 216 cubic inch automobile engine with a standard carburetor and is used to determine the relative amounts of deposits on intake valves, which valves operate relatively dry, i.e., without oil flooding, using various fuels. The engine is operated for 40 hours at 2500 r.p.m. with a load of 20 brake horsepower. Cooling water is circulated through the cooling system of the engine at a rate such that with F. water entering the engine, the water leaving the engine is F.i5 F. The oil is maintained at a temperature of Fri-5 F.

Following completion of the 40-hour run the intake valves are removed, the surfaces of the valves facing the combustion chamber are scraped and/or buffed free of deposits and the valves are then washed with naphtha to remove naphtha-soluble materials. The amounts of naphtha-insoluble deposits on the fillet and adjacent stem area is determined by weighing. This test, although it does not give absolute values, does give comparative data from which the effectiveness of various gasoline additives in preventing or reducing deposition on intake valves can be evaluated. The results are reported as naptha-insoluble deposits per 6 valves.

In this test it is believed that the deposits are largely from the fuel rather than the crankcase oil. This conclusion is reached since the intake valves operate with a minimum of lubrication and therefore very little crankcase oil reaches the valve tulips. The data shown on the following Table 1V were all obtained using an SAE 20 heavy duty crankcase oil. The only variations were in the fuel employed. Fuel compositions, with the exception of fuel No. 21, are those shown in Table II.

Table IV Road Load Detergency Test Fuel Naphtha Insoluble Intake Valve Deposits A vernge, No. Composition grams/valve PART 1 1- 0.25 14. 0. 24 21 Commerical Premium Gasoline 0. 61

PART 2 a A commerical gasoline of 97 knock rating containing lead, a guru inhibitor and a commerical detergent additive.

Part 1 of Table IV shows that whereas gasolines which do not contain additives other than the conventional additives such as tetraethyl lead and gun inhibitor permit the formation of but relatively small amounts of intake valve deposits, a commercial gasoline containing detergent I claim:

1. An internal combustion engine fuel consisting essentially of hydrocarbons boiling in the gasoline boiling range containing between about 0.00005 and about 0.5% by Weight of the salt of a hydrocarbon diester of phosphoric acid in which the hydrocarbon groups contain between 6 and 22 carbon atoms and and aliphatic hydrocarbon diamine having not more than one N-hydrocarbon substituent, said fuel containing also between about 0.006% and about 0.6% by weight of a parafimic hydrocarbon oil having a viscosity at 210 F. between 42 and 78 SSU and a flash point of at least 400 F.

2. A fuel according to claim 1 in which said salt is the salt of a dialkyl phosphate and an aliphatic diamine of the formula in which X represents an alkyl radical obtained from fatty alcohols.

3. A fuel according to claim 2 in which X represents alkyl radicals obtained from tallow fatty alcohols.

4. A fuel according to claim 2 in which X represents alkyl radicals obtained from soya fatty alcohols.

5. A fuel according to claim 2 in which X represents alkyl radicals obtained from coconut fatty alcohols.

6. An internal combustion engine fuel consisting essentially of hydrocarbons boiling in the gasoline boiling range containing a small amount, sufficient to impart detergency to said gasoline, of the salt of a hydrocarbon diester of phosphoric acid in which the hydrocarbon groups contains between 6 and 22 carbon atoms and an aliphatic hydrocarbon diamine having not more than one N-hydrocarbon substituent, said fuel containing also between about 0.006% and about 0.6% by weight of a paraflinic hydrocarbon oil having a viscosity at 210 F. between 42 and 78 SSU and a flash point of at least 400 F.

7. A fuel according to claim 6 in which said salt is the salt of a dialkyl phosphate in which the alkyl radicals contain between 6 and 22 carbon atoms and an N-alkyl substituted alphatic hydrocarbon diamine having not more than one N-hydrocarbon substituent.

8. An internal combustion engine fuel consisting essentially of hydrocarbons boiling in the gasoline boiling range containing between about 0.00005 and about 0.5% by weight of a compound having the formula RO R 1 2" in which R and R each represents a radical of the class consisting of alkyl, cycloalkyl, alkylene and alkaryl radicals having 6 to 22 carbon atoms, R" and R' each represents a member of the group consisting of hydrogen and alkyl, cycloalkyl, and alkylene radicals having 6 to 18 carbon atoms, R represents a member of the group consisting of hydrogen and an alkyl radical of 1 to 4 carbon atoms, and x is an integer of 1 to 5, the total carbon atom content of the (OHz)r-CH group being between 2 and 10 carbon atoms, said fuel containing also between about 0.006% and about 0.6% by weight of a paraffinic hydrocarbon oil having a viscosity at 210 F. between 42 and 78 SSU and a flash point of at least 400 F.

9. A fuel according to claim 8 in which said compound is a salt of dioleyl phosphate and 1,2-propylene diamine. I

10. A fuel according to claim 8 in which said compound is present in amounts between about 0.0004% and about 0.05% by weight.

11. An internal combustion engine fuel consisting essentially of hydrocarbons boiling in the gasoline boiling range and containing up to 5 ml. of tetraethyl lead per gallon; between about 2 and about 40 pounds per 1000 barrels of a gum inhibitor selected from the class consisting of aromatic amines, aromatic hydroxy amines and hydroxy aromatic amines and between about 0.00005 and about 0.5% by weight of a compound having the formula RO R" I l" in which R and R each represents a radical of the class consisting of alkyl, cycloalkyl, alkylene and alkaryl radicals having 6 to 22 carbon atoms, R and R each represents a member of the group consisting of hydrogen and alkyl, cycloalkyl, and alkylene radicals having 6 to 18 carbon atoms, R represents a member of the group consisting of hydrogen and an alkyl radical of 1 to 4 carbon atoms, and x is an integer of 1 to 5, the total carbon atom content of the group being between 2 and 10 carbon atoms, said fuel containing also between about 0.006% and about 0.6% by weight of a parainnic hydrocarbon oil having a viscosity at 210 F. between 42 and 78 SSU and a flash point of at least 400 F.

References Cited in the file of this patent UNITED STATES PATENTS 1,682,561 Hennen Aug. 28, 1928 2,107,233 Burwell Feb. 1, 1938 2,297,114 Thompson Sept. 29, 1942 2,654,697 Andress et al. Oct. 6, 1953 2,728,647 Vaughn Dec. 27, 1955 2,798,045 Buck et al. July 2, 1957 2,848,414 Chenicek Aug. 19, 1958 2,857,334 Thompson Oct. 21, 1958 2,863,744 Cantrell et a1. Dec. 9, 1958 2,863,745 Cantrell et al. Dec. 9, 1958 2,863,904 Cantrell et al. Dec. 9, 19 58 

1. AN INTERNAL COMBUSTION ENGINE FUEL CONSISTING ESSENTIALLY OF HYDROCARBONS BOILING IN THE GASOLINE BOILING RANGE CONTAINING BETWEEN ABOUT 0.00005% AND ABOUT 0.5% BY WEIGHT OF THE SALT OF A HYDROCARBON DIESTER OF PHOSPHORIC ACID IN WHICH THE HYDROCARBON GROUPS CONTAIN BETWEEN 6 AND 22 CARBON ATOMS AND AND ALIPHATIC HYDROCARBON DIAMINE HAVING NOT MORE THAN ONE N-HYDROCARBON SUBSTITUENT, SAID FUEL CONTAINING ALSO BETWEEN ABOUT 0.006% AND ABOUT 0.6% BY WEIGHT OF A PARAFFINIC HYDROCARBON OIL HAVING A VISCOSITY AT 210*F. BETWEEN 42 AND 78 SSU AND A FLASH POINT OF AT LEAST 400*F. 